The military in the 21st Century needs a more responsive, more versatile, more lethal, more survivable, and more sustainable force. This modern military force will require more electric power that is available in theater any where any time. At the same time, it is beneficial to use materials which reduce the load (by weight) that needs to be carried into the battlefield for ease of mobility and to reduce transportation requirements.
Currently the military depends on its logistics fuel, JP-8, a kerosene based jet fuel which has the highest energy density as energy source, to meet most of the power needs in battlefield. Since the fuel consumption has been increased more than ten fold over the last half century by the Army during war time, the reduction of logistics burden is in urgent need and development of advance energy conversion technology is highly desirable to meet the great power demand in today's battlefield.
Fossil fuels, such as petroleum based logistics fuel and abundant coal, usually contain sulfur impurities. Power generation processes from fossil fuels in most cases will produce some form of sulfur compounds as by-product(s). This sulfur containing by-product(s) is not only detrimental to the function of electrochemical device such as fuel cell, but is also environmentally unfriendly. Effective and efficient removal of sulfur by-product(s) from fuel stream is an essential step for any type of fossil fuel based power generation system that requires zero or near zero level of sulfur compound(s) in the consumed fuel.
One way to achieve the goal is to develop a capability to effectively and efficiently convert JP-8 to electricity so that overall fuel consumption can be reduced. Fuel cell generation of electricity in battlefield directly by JP-8 through fuel reformation is a promising technology currently under intense development. As mentioned above, sulfur impurities must be removed from the fuel stream before feeding to fuel cells and desulfurization is one of the crucial steps that may enable the advanced technology for electricity generation by hydrocarbon fuel in battlefield. Materials used in the desulfurization component require (a) a high capacity to adsorb as much as possible of hydrogen sulfide molecule per unit weight; and (b) stable and functioning at temperature as close as to the operating temperature of both the fuel reformer and the fuel cells, that is, 600 to 800° C. Zinc oxide based sorbent materials are widely used for desulfurization including hydrogen sulfide removal. Unfortunately, they are only suitable for applications at below 600° C. in reducing atmosphere such as hydrogen rich reformate and in presence of water vapor that is one of the products in the hydrocarbon fuel reformate.
JP-8 is merely an example of a type of fuel for which the present invention may be utilized. Other examples include types of fossil fuels such as diesel fuel and gasified coal.